This invention relates to a vapor compression refrigeration system and, in particular, to a refrigeration flow distributor for improving the performance of a vapor compression refrigeration system.
The vapor compression refrigeration system typically involves a pair of heat exchangers that are operatively connected into a circuit for circulating refrigerant through the units. One unit acts as an evaporator in the system while the other acts as a condenser. The suction side of a compressor is connected to the refrigerant outlet of the evaporator unit and is arranged to bring the refrigerant leaving the evaporator to a higher temperature and pressure before introducing the refrigerant into the condenser unit. In the condenser, the high pressure refrigerant is brought to a liquid state and it is then throttled to a lower temperature and pressure in an expansion device prior to being circulated through the evaporator unit. The two phase refrigerant mixture passing through the evaporator unit is brought into heat transfer relationship with a higher temperature substance, such as air or water, whereby the refrigerant absorbs energy from the higher temperature substance and thus produces the desired chilling.
The performance of the evaporator unit, and thus the overall performance of the system, is dependent to a large extent on the ability to uniformly distribute the two phase mixture throughout the evaporator unit. In the evaporator unit, the two phase mixture is typically routed through a series of parallel flow channels that are coupled to an inlet supply header. Some of the flow channels are stationed some distance from the refrigerant inlet and, because of poor distribution, receive more gas phase than those channels closer to the inlet. As a consequence, the heat performance of the unit is adversely affected and a nonuniform distribution of heat transfer occurs across the unit.
Efforts directed toward enlarging the evaporator units used in vapor compression systems in order to enhance the systems' performance have not proven to be very successful and have resulted in a considerable increase in the cost of these systems. Attempts have also been directed toward mounting restricted orifices or rings at the entrance to each refrigerant flow channel within a system's evaporator unit to improve refrigerant distribution within the unit and thus improve the system's performance. Here again, some improvement can be realized, but only at an increased cost. It has also been suggested that a flow distributor be mounted in the refrigerant supply line linking the expansion device and the refrigerant inlet to the evaporator unit. These devices, however, are for the most part difficult and costly to manufacture and cannot be retrofitted to existing systems.